Biomimetic approach to the formation of titanium dioxide thin films by using poly(2-(dimethylamino)ethyl...

We demonstrate that the biomimetic method-which has been used for the formation of silica thin films-also could be applied directly to the formation of titanium dioxide (TiO(2)) thin films, which are technologically important materials because of their applications to photocatalytic purifiers, photochemical solar cells, and others. After generation of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) films on gold surfaces by surface-initiated polymerization, titanium bis(ammonium lactato)dihydroxide was used as a precursor of TiO(2). The TiO(2)/PDMAEMA films were successfully formed on the surfaces in aqueous solution at neutral pH (pH 6.7) and room temperature, and were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and X-ray diffractometry. The formed TiO(2) films have an amorphous nature and large area uniformity in thickness. The degree of crystallization was controlled by annealing. We also investigated the pH effect and the phosphate incorporation in the films by using phosphate-buffered solutions. The TiO(2) films were formed in all the employed pH values in the range of 2 to 12, but phosphate anions were found to be incorporated into the films facilely only at low pH.